Integration using multiple formula's and a single variable.

Question

Tim Stark 2018-11-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/430840-integration-using-multiple-formula-s-and-a-single-variable

评论： Star Strider 2018-11-19

采纳的回答： Star Strider

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Hi Guys,

I have a question regarding these lines of code:

d = @(t) d0.*cos(2.*pi.*((t-172)./365));
c = @(d,t) sin(La).*sin(d)+cos(La).*cos(d).*cos(2*pi.*(t-0.5)-Lo);
f = @(c) c.*a0+a1.*exp(-(k./c));
Nf = integral(f,0,365);

I want to integrate the function f over t=0 to t=365. However, the function f is also dependent on formula c and d.

The way I have set it up now, f is integrated over c=0 to c=365. How can I do this?

t is the only variable, the others (La, Lo, etc) are all constants.

Thanks in advance!

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Answer 1

Star Strider 2018-11-19

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https://ww2.mathworks.cn/matlabcentral/answers/430840-integration-using-multiple-formula-s-and-a-single-variable#answer_347888

在 MATLAB Online 中打开

You are actually integrating with respect to ‘t’. Express all your functions as function of ‘t’, and it should work.

However, this returns:

Warning: Infinite or Not-a-Number value encountered.

so you need to solve that problem.

d = @(t) d0.*cos(2.*pi.*((t-172)./365));
c = @(t) sin(La).*sin(d(t))+cos(La).*cos(d(t)).*cos(2*pi.*(t-0.5)-Lo);
f = @(t) c(t).*a0+a1.*exp(-(k./c(t)));
Nf = integral(f,0,365);

This is the correct approach.